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Yi Mao, MITCollaborators: Max Tegmark, Alan Guth,
Matias Zaldarriaga, Matt McQuinn, Oliver Zahn, Tom Faulkner, Ted Bunn, Serkan Cabi
Constraining cosmological and gravitational parameters with upcoming astrophysical data
What do we learn in cosmology?
Yi MaoFermilab seminarJanuary 23, 2008
0th order:Expansion
a(t)k
H(z)
Yi MaoFermilab seminarJanuary 23, 2008
Distant light is {dimmed
redshifteddistance Vs. z H(z)
1st order:Clustering
Cl, P(k), …
Yi MaoFermilab seminarJanuary 23, 2008
CMBZ ~ 1089
Galaxy surveys
z 1Supernovae IaGravitational Lensing Ly-a forest
But the best is yet
to comePrecision CMB (polarization, small scales), precision lensing ……
and 21cm tomography
Yi MaoFermilab seminarJanuary 23, 2008
CMBZ ~ 1089
Galaxy surveys
z 1Supernovae IaGravitational Lensing Ly-a forest
21cmtomography
Yi Mao
Fermilab seminarJanuary 23, 2008
Murchison Widefield Array (MWA)• Located in western Australia • 500 antennas; array diameters 1500m; • Measures z=6~12
Murchison Widefield Array (MWA)• Located in western Australia • 500 antennas; array diameters 1500m; • Measures z=6~12
Yi Mao
Fermilab seminarJanuary 23, 2008
Other arrays• Square Kilometre Array (SKA)• Low Frequency Array (LOFAR)• 21cm Array (21CMA)
• Square Kilometre Array (SKA)• Low Frequency Array (LOFAR)• 21cm Array (21CMA)
21cm line from the Epoch of
Reionization
Yi MaoFermilab seminarJanuary 23, 2008
QuickTime™ and aYUV420 codec decompressor
are needed to see this picture.
Yi Mao
Fermilab seminarJanuary 23, 2008
21cm Power spectrum21cm Power spectrum
• 21cm power spectrum is not isotropic because of redshift space distortion!
• 21cm power spectrum is not isotropic because of redshift space distortion!
How accurately can 21cm tomography
constrain cosmological parameters?
Yi MaoFermilab seminarJanuary 23, 2008
Yi Mao
Fermilab seminarJanuary 23, 2008
Yi Mao
Fermilab seminarJanuary 23, 2008
YM, Tegmark, McQuinn, Zaldarriaga & Zahn (2008)
K
Yi Mao
Fermilab seminarJanuary 23, 2008
YM, Tegmark, McQuinn, Zaldarriaga & Zahn (2008)
K
Ionization power spectrum modeling
Yi MaoFermilab seminarJanuary 23, 2008
Yi Mao
Fermilab seminarJanuary 23, 2008
OPT
Yi Mao
Fermilab seminarJanuary 23, 2008
PESS
Yi Mao
Fermilab seminarJanuary 23, 2008 YM, Tegmark, McQuinn, Zaldarriaga & Zahn (2008)
MID
Yi Mao
Fermilab seminarJanuary 23, 2008
YM, Tegmark, McQuinn, Zaldarriaga & Zahn (2008)
K
Optimal array configuration
Yi MaoFermilab seminarJanuary 23, 2008
Yi Mao
Fermilab seminarJanuary 23, 2008
LOFAR MWA SKA
MID
OP
T
Size of compact core
Siz
e of
tot
al in
ner
core
YM, Tegmark, McQuinn, Zaldarriaga & Zahn (2008)
Size of compact core
Siz
e of
tot
al in
ner
core
MWA in OPT model
YM, Tegmark, McQuinn, Zaldarriaga & Zahn (2008)
Yi MaoFermilab seminarJanuary 23, 2008
Future: 3D neutral hydrogen maps?
Yi MaoFermilab seminarJanuary 23, 2008
Testing gravity in a general framework
Yi MaoFermilab seminarJanuary 23, 2008
Generalize PPN
• A general geometry is determined by metric (g) and connection (), both independent of each other.
• Three quantities characterize the departure from Minkowski spacetime:
Yi MaoFermilab seminarJanuary 23, 2008
Gen
eral
ized
geo
met
ry f
amily
tre
e
Constraining torsion
Yi MaoFermilab seminarJanuary 23, 2008
Parametrization of torsion around Earth
to linear order in m and a
Constraining torsion with GPB
Image from http://einstein.stanford.edu
Constraining torsion with GPB
YM, Tegmark, Guth, Cabi (2006)
Constraining f(R) gravity
Yi MaoFermilab seminarJanuary 23, 2008
Yi Mao
Fermilab seminarJanuary 23, 2008
Solar system constraints on f(R) Chameleon
Faulkner, Tegmark, Bunn and YM (2007)
Yi Mao
Fermilab seminarJanuary 23, 2008
Constraints on cubic f(R) model
Faulkner, Tegmark, Bunn and YM (2007)
Yi Mao
Fermilab seminarJanuary 23, 2008
Outlook
• 3D HI mapping: direct view into the dark ages, precision constraints on cosmological parameters
• Better understanding of the Epoch of Reionization• New tests of Einstein gravity on scales from the solar
system to the cosmos• Common question for cosmology and gravitation: Dark energy = cosmological constant or modified gravity? Dark matter = new particles or TeVeS/MOND? Can GR (and standard cosmological model) be further
tested?
Tegmark & Zaldarridaga, astro-ph/0207047+updatesYi Mao
Fermilab seminarJanuary 23, 2008
Yi Mao
Fermilab seminarJanuary 23, 2008
21cm line21cm line
•
• Spin temperature , where
• Emission if Ts > Tcmb; absorption if Ts < Tcmb• Saturated when Ts >> Tcmb; arbitrarily large when Ts << Tcmb• The last factor makes the anisotropy!
•
• Spin temperature , where
• Emission if Ts > Tcmb; absorption if Ts < Tcmb• Saturated when Ts >> Tcmb; arbitrarily large when Ts << Tcmb• The last factor makes the anisotropy!
Yi Mao
Fermilab seminarJanuary 23, 2008
Ts couplingsTs couplings
• Absorption of CMB photons and stimulated emission
• Collisions with H, e, p: Ts Tk
• Scattering of UV photons( the Wouthuysen-Field Effect): Ts TLya
• Absorption of CMB photons and stimulated emission
• Collisions with H, e, p: Ts Tk
• Scattering of UV photons( the Wouthuysen-Field Effect): Ts TLya
Furlanetto, Oh & Briggs 2006
Yi Mao
Fermilab seminarJanuary 23, 2008
• zdec~150: compton heating.
Tk = Tcmb before zdec; Tk~(1+z)2 after.
• Z1: Ts = Tk before z1; Ts Tcmb after.
• Zh: IGM Tk > Tcmb.
• Zc: Wouthuysen-Field Effect couples Ts = Tk again.
• Zr: reionization.
• zdec~150: compton heating.
Tk = Tcmb before zdec; Tk~(1+z)2 after.
• Z1: Ts = Tk before z1; Ts Tcmb after.
• Zh: IGM Tk > Tcmb.
• Zc: Wouthuysen-Field Effect couples Ts = Tk again.
• Zr: reionization.
Thermal histroy of IGMThermal histroy of IGM
